1. Field of the Invention
This invention relates to a process for producing an aqueous liquid dispersion of polymers.
2. Description of the Prior Art
An aqueous liquid dispersion of polymers is broadly useful as a water-based paint, printing ink, fiber processing aid, paper processing aid, leather processing aid, bonding agent and tackifier. The water-based paint is promising for future, use because there is no fear of pollution and exhaustion of supplies of water.
One of the known methods for producing an aqueous liquid dispersion of polymers comprises subjecting vinyl-type monomers whose polymers are insoluble in water or a mixed solution of water and an aqueous organic solvent, to graft polymerization in the presence of a dispersion stabilizer which is soluble in water or a mixed solution of water and an aqueous organic solvent.
For example, as a dispersion stabilizer, there are mentioned maleinized polybutadiene in Japanese Patent Publication No. SHO 49-43381, water soluble unsaturated polyester in Japanese Patent Publication No. SHO 53-9795 and water soluble polymer in the molecule of which polymerizable vinyl groups are introduced in Japanese Laid-Open Publication No. SHO 53-17680.
These methods have faults in that the processes not only are complicated, but also, because the polymerization yield thereof in the block polymerization process is low, the reaction time thereof is long, the productivity is low and the dispersion stability and the storage stability of the liquid dispersion are bad. When maleinized polybutadiene or unsaturated polyester is employed as a dispersion stabilizer in producing a liquid dispersion, the resultant liquid dispersion has faults in that when it is used for e.g. painting, a uniform painting film cannot be obtained with ease and the exterior durability thereof is bad.